Ronaldo joined Spanish giants Real Madrid from Premier League powerhouse United in the summer of 2009.
The Portugal international forward is widely recognised as one of the two best players in the world.
Clement, who is now in charge of Championship side Derby, worked with the 30-year-old at Madrid for two years as a first-team coach.
The Englishman does not believe that Ronaldo will return to England.
“I’m not sure (if Ronaldo will come back to England),” Clement told The Sun. “He’s at a wonderful club, he’s doing really well there, he’s winning trophies, he’s breaking all the records and has a great lifestyle there. It makes sense for him to stay there and continue. It’s down to him.”
Ronaldo joined United from Portuguese side Sporting Lisbon in 2003 and played for the Red Devils for six years.
The Portuguese established himself as one of the best players in the world during his time at Old Trafford.
Ronaldo has taken his game to a new level since joining Madrid in 2009, and it is hard to see him leave Los Blancos for any other club.